How to use a one knob compressor

hello this is Bruno loose with glv productions thanks for joining me in this video we're going to look at how to use a one knob compressor so let's begin alright now before we begin the video let me just give you a very quick overview of what we have here we have our mg 1:24 CX mixing console over here we have an audio technica a 5100 plugged into channel 4 and that's the mic that I'm speaking to you through now it's up here and that's just to pick up my voice on channel 2 we have an sm57 I know the label says 58 that's from a previous video and inserted on channel 2 is channel 3 of the dbx 1046 oh and of course the output of the mix is connected to the video camera automatic gain control on the mixer is disabled so that the dynamics that you hear are as a result of our setup okay so let's begin by looking at the controls on a typical hardware compressor which you can see here so this is channel 3 at the dbx 1 0 4 6 and as you can see it has 4 knobs on the front it has a threshold a ratio an input gain and finally it has a limiter now the limiter is not found on all compressors so we'll just keep that off for this demonstration the important thing to understanding compression is to understand the concepts of threshold and ratio and in order to do that I have a little diagram here you have level on this axis and time on this axis you have a signal that increases in a linear fashion with respect to level and time now when we talk about compression threshold it refers to the point in dB at which the compression begins or kicks in the ratio refers to the ratio of the input to the output signals once the input crosses the threshold so a ratio of 1 is to 1 is the same as no compression a ratio of 2 is to 1 means that for every 2 dB that the input signal exceeds the threshold the output signal will only increase by 1 DB so for every 6 DB increase in the input over the threshold you'll get a 3 DB increase in the output a 4 is to 1 ratio is double 2 is to 1 and means that for every 4 DB over the threshold that the input signal goes your output signal will only increase by 1 DB so 2 is 2 1 typical studio compression 4 is 2 1 is what you might use in a live setting for certain uses and this diagram shows you graphically how the signal is affected ok so now that we understand how it works in theory let's have a look at how it works in practice as you can see on the front panel we have our threshold marked in DB and we have our ratio so to begin with I'm going to set this to 2 is to 1 and the output gain also referred to as makeup gain this refers to gain that it is that is applied after the compression but let's just get some compression happening first so I'm going to pick up this sm57 which is connected to channel 2 of the mixer check check 1 2 ok now to begin with I'm going to set my threshold very high I'm going to set it at 0 DB so as you can see that we currently have no compression all right so in other words the input signal has not yet gone over the threshold as I bring my threshold down you can see that I begin to have gain reduction in other words compression is happening and you'll hear this on the video as I continue to go down you can see that I get more and more compression there okay and this is reducing the loudest peaks of my voice now all right now I'm going to give you an illustration of what happens during compression using my hands now if you look at this if you assume that my right hand represents the bottom of the dynamic range in other words this is the softest signals and my left hand represents the top of the dynamic range these are the loudest signals when compression kicks in what happens is that the loudest signals are reduced right the loudest signals are reduced a lot of people think that compresses make louder signal softer and softer signals louder that is not strictly true okay so what we have done is we have reduced the loudest signals that's the gain reduction that you can see on the meter then what we do is we can turn the whole signal up thereby increasing the average level of the signal okay that process is done either at the fader or at the output gain or make up gain button on the compressor so let's repeat the process we have two is two one no compression bring the threshold down until you can see there we have quite a bit of compression happening and you can hear that my voice is getting softer what I'm now going to do is I am going to increase the output gain to bring up the average level okay so you can now see that if I use this switch here to compare our input and our output signals on now about 0db without this the input signal is about zero but the output is only -12 because of the compression so we need to increase this in order to give us the same input and output signals this is why people think that compression makes louder signal softer and softer signals louder it's actually a two-stage process the compression is the gain reduction the make up or output gain then raises the average level and now with a one knob compressor you have only a single control you don't have separate threshold and ratio controls so it's important to read the owner's manual to see what those are now on this particular mixer they've been real helpful and printed them over here with the control fully counterclockwise like it is now the gain is zero and the threshold is plus 20 now there's no mention of ratio I looked it up in the owners manual the ratio goes from 1 is to 1 to 4 is to 1 you have no control over that with the control fully clockwise you have 9 DB of gain and the threshold is at minus 5 dB you so what that means is is that the one knob compressor combines the functions of ratio threshold and output gain as you turn this knob clockwise what you're doing is you're simultaneously lowering the threshold increasing the ratio and increasing the output gain so what we're going to do now is I'm going to change over check check one two here we are on the dynamic microphone speaking to you on channel 2 and right now what we've got is we've got the one knob presser turned fully off as I turn the knob clockwise you hear that the average level goes up and the second thing is you'll hear that the peaks are not back so check one two check check one two three four check one two so that's at 12 o'clock check one two three four now notice that on the meters the meters are showing a higher average level okay once again all the way off we're at about minus three at three o'clock we're now at about plus three check check one two check one two check check one two so you can hear that's maximum compression and as you can hear what's happened is the average level of my voice has gone up quite a bit let's now try that on the condenser microphone no compression check check one two three four check one two going up check check one two one two one two check one two one two one two check 1 2 so the final question is how do you set a 1 knob compressor you've got no output or input metering on the compressor itself so what that means is that you've got no way of knowing how much gain reduction you have all you have are the meters on the console to guide you and when you have a whole band playing it's almost impossible to tell how much compression each channel is getting so my advice to you is set it using your ears when you're setting up the channel try and experiment with different settings try the knob at 10 o'clock 12:00 to 3:00 and see what sounds best remember also that as you turn the knob clockwise you are effectively raising the game so if you go too far you can clip the channel or you can get feedback beyond that you need to use your ears and your experience to set these things I generally start with them at 12 o'clock and I'll adjust from there so that was how you use a one knob compressor I hope that it's helped your understanding of this particular piece of equipment as well as compression in general if you have any questions or comments do please leave them in the comment section below I always love hearing from you my viewers and subscribers until the next video this is Bruno Luce with gel B productions take care and God bless you goodbye

Channel: GLB Productions

Views: 277,819

Keywords: sound system, sound reinforcement, compression, compressor, gain reduction, threshold, ratio, make up gain, Audio-Technica AE5100, Shure SM57, MG124CX, Yamaha, mixer, mixing console

Id: YpOZcaT3txM

Length: 11min 50sec (710 seconds)

Published: Mon Nov 14 2016